Caralynn is a writer, native New Yorker, TV enthusiast, and dog mom to Hobbes.

The hit Starz series Outlander is one of the sexiest shows on TV.

The historical time travel drama follows a married World War II nurse, Claire Randall, who accidentally travels back in time 200 years and falls in love with a dashing Scotsman, Jamie Fraser, in the 1700s. Outlander (which is based on a series of novels by author Diana Gabaldon) has won the hearts of fans all over the world over the course of its three seasons. They faithfully tune in every week when the show is airing — largely to see the incredible chemistry between the show’s lead actor and actress, Sam Heughan and Caitriona Balfe.

Anyone who watches the show knows about the legendary, electric chemistry between Sam and Caitriona, who have clocked quite a few extremely intimate love scenes. Recently, Outlander‘s showrunner shared (via Entertainment Tonight) a special gift with the show’s fans: Sam and Caitriona’s very first on-screen chemistry test!

The chemistry test is an important early part of any show’s casting process, when the people creating it get to see how two actors work together onscreen. As you can imagine, that’s an especially vital step for a series that centers on a romantic relationship, like Outlander!

Sam was first cast as Jamie in July 2013, according to Deadline. The Outlander team tested potential Claires against him until Caitriona was finally announced as the female lead in September of the same year.

“We were looking for chemistry between the two characters,” Outlander executive producer Ronald D. Moore told Entertainment Tonight before introducing the throwback clip. “We really felt that Cat was probably going to be the one, but this was the final moment. This was when she literally sealed the deal and got the show.”

Check out the screen test in the video below, and don’t forget to SHARE it on Facebook with other Outlander fans!